A lens tube described in PTL 1 includes a holder (fixed cylinder) fixed to a substrate to which a CCD (charge coupled device) is mounted and a barrel (cam cylinder) that houses a lens. The barrel is fixed to the holder such that the optical axis of the CCD is aligned with the optical axis of the lens. The lens tube has an elastic piece disposed in the holder so that the barrel is biased by the elastic piece, thereby preventing backlash of the barrel.